Independent · Source-led · American performance history Issue 01 · 1951–2023
American Muscle Car Facts

Showroom arguments.
Race-bred answers.

General Motors option code

391  — Safe-T-Track differential

391 (Safe-T-Track differential): a General Motors factory option code recorded on 1 model across 1976, with installs and price where a source states them.

1 model · 1 model year · 1 source

Yellow 1976 Formula Firebird with twin hood scoops and Formula lettering on its lower doors, on a pale yellow brochure page
1976 Pontiac Formula Firebird hardtop coupe in yellow (1976 Pontiac brochure)

Every sourced appearance

Year Model As named that year Price Installs
1976 Pontiac Firebird and Trans Am Safe-T-Track differential sales code $51 66,133 Reported

Every row traces to the source it links from on that model's own year page; this table only collects them in one place.